A primary concern in the construction, operation and maintenance of nuclear power generating facilities is the possible hazard of exposure to harmful levels of radiation. In response to both public and private concern for safety to humans and the environment, an operating nuclear facility is required to undergo frequent inspections and periodic preventative maintenance to quickly identify components requiring adjustment, troubleshooting, removal or replacement. Often, this requires a maintenance team to enter and spend a significant amount of time conducting inspections and repairs in hot-zones such as the nuclear reactor area.
This regular maintenance includes periodic removal of numerous motor operators for valves from the hot-zone for inspection and repair. In so doing, all electrical connections, such as cables and conductors extending from the motor operators to the plant control board, must be disconnected or determinated at the valve. Repeated disconnection, reconnection and pulling of conductors commonly results in damaged or broken lugs, terminals, wires and conductor insulation. These damaged parts must be repaired or replaced in the hot-zone before the motor operator is reinstalled, thereby prolonging the workers' exposure to harmful levels of radiation.
Currently, damaged conductor insulation is commonly repaired using a heat shrinkable Raychem patch over the damaged area. Since the addition of a heat shrinkable patch increases the overall diameter of the insulation on the conductor, a tighter constraint is created between the adjacent cables. This additional constraint heightens the probability that further damage to the electrical conductors will occur during subsequent handling.
When damage to the connections is minor, lugs can be replaced and conductors can be cut back behind the damaged area. Both of these procedures decrease the length of the conductor and its cable. After repeated repairs, the remaining cable becomes too short to reach the valve and must be replaced. Replacement of a cable usually requires that the old cable be pulled from its hot-zone termination at the valve back to its initial termination in the cable spread room. Typically, the cable spread room is several hundred feet away from the motor control area. Therefore, both old and new cables must be pulled and reinstalled through various levels of the plant and through numerous penetrations of the nuclear facility's interior concrete walls. These penetrations must then be resealed for fire prevention and contamination protection.
The present system and method of maintaining electrical connections from the control board to the motor operators result in costly and time consuming hot-zone repairs with much down time delay. There exists an immediate need for an improved system and method for the construction, maintenance and repair of the motor operator and the electrical connections attached thereto which limits workers' exposure to dangerous levels of radiation. The present invention meets this need.